TWIZEL, SOUTH ISLAND, NEW ZEALAND--I'm standing in the middle of a huge grassy field, surrounded by scores of fully armed and heavily armored Rohan warriors on horseback.

In the distance, a sea of masked and muddied Orcs get ready to rumble with Rohan. As a horse tries to eat my Dictaphone, we're invited off the field before we're trampled.

This is LOTR's biggest day yet--230 Orcs, 250 Rohan warriors and 50 or so stunt players are here in this remote South Island mountain village to fight out the Battle of Pelennor Fields from the end of Book Three.

Unlike the grand sets of Edoras, Pelennor is strictly minimalist--just a grassy field at the foot of snow-capped mountains. Because of the set's remoteness, everything--offices, toilets, camera equipment, power generators, sets--has been brought in by truck or plane.

The location is a three-hour drive from the nearest airport, in Christchurch. We flew here in a tiny single-engine plane. Our pilots make the journey in and out of the set each day, carrying urgent cargo, deliveries and the all-important rushes (daily film footage) for inspection by LOTR bigwigs.

With nearly 800 people and 250 horses on set, the atmosphere is like a military operation. Extras are divided into six groups and start arriving at 4:30 a.m. We follow 30 sleepy extras into tents, where costumers, makeup artists and mud-wielding WETA technicians will transform them into Orcs: the pond scum of Middle Earth.

Earlier arrivals, already dressed, fed and made up, are outside, getting their marching orders from a physical trainer. Within half an hour, they're learning to walk like an Orc.

Each new arrival gets an identity number and a plastic sack (to preserve their masks) and is led to makeshift dressing rooms, where they don black nylon bodysuits. Over this, the WETA folks put them into spongy gray rubber Orc skin. The actual costumes and armor are added later.

"They're foot soldiers--they scavenge through the bodies of their victims and steal bits of clothing," she explains. "So, we can borrow from other costumes we've got."

The mix of clothing scraps, piecemeal armor and individually crafted rubber mask gives each Orc his own look. Makeup artists give a quick smear of black or gray makeup around the eyes, then it's on with the masks. Finally, the WETA techs slap on specially designed non-toxic mud and dark blood, and our new Orcs are ready for breakfast.

With so many warriors to feed, meals are another major operation. Colin the Caterer provides the rundown: 50 kilograms of bacon, 1,440 eggs and 400 loaves of bread.

In all, some 800 kilograms of food is cooked each day on the site by 18 full-time staffers, using massive ovens hooked up to mobile generators. Refrigeration units are stocked top to bottom. There's also plenty of fresh fruit and vegetables from nearby farms and towns.

Back on set, the Orcs collect their weapons from a cart called Sergeant Slaughter's Mobile Orc Unit, then get taken through their paces. With such huge man and horsepower on hand today, safety is a crucial consideration. Extras are encouraged to opt out at any stage if they feel uncomfortable or unwell. But everyone, including the horses, is raring to go. It's time for battle, baby.

The Orcs are lined into widely spaced rows across a grassy field. Some 300 meters north is a similar row of horses. The Rohan will charge toward the Orcs, riding between the rows, as the Orcs simulate battle on the spot.

No one will actually connect, but to the camera (shooting from the side), it will seem like a mighty bust-up. One fixed camera shoots from ground level to catch close-up action. Another camera "rides" alongside the charging horses on a moving truck.

The crew preps the shot as the extras position themselves into lines. WETA crew members do last-minute touch-ups, smearing the Orcs with (of all things) KY jelly to give them a slimy gleam.

In the distance, techies send up huge streams of white, incense-laden smoke. As cast and crew pause, waiting for the call, there's a brief, death-like moment of silence.

The Orcs get their cue first. Growling and crying like wild animals, they whirl around their weapons, winding themselves up like WWF gladiators.

King Theoden of Rohan (actually, his riding double) leads the throng. He wears armor embossed with a horse insignia over a chain-mail vest, an embroidered emerald green tunic and a massive, Viking-like helmet, also with a horse insignia.

Hoisting their banners, the Rohirrim gallop toward the Orcs. Picking up speed, the horses send up billows of dust as they thunder down the plain. Close to the cameras, stunt players simulate fighting moves, coming in close to attack the horses or crashing with injuries. Proud and aggressive to start, the Orcs fall back in terror under the weight of the Rohirrim army.

Although carefully choreographed, it's a stunning pandemonium, with a rush of screams, hammering hooves, sun glinting on armor and the sheer force of hundreds of conflicting bodies.

With the first take down, cast and crew are visibly relieved. Everyone reassembles for the second shot, while WETA people rush the set to water down and relube the sweaty Orcs. Amid the chaos, one of the Orcs has lost a shoe. It's discreetly removed from the battlefield, and the shoeless Orc is located and refitted.

WETA head Richard Taylor is beaming like a schoolboy. "It's a great day for WETA," he tells me, proudly surveying his 200 ugly, greasy babies. He encourages the extras to move more, breaking spontaneously into an Orc body slam to demonstrate his point. "You are not human beings!" he yells. "You are scum!"

The second shot goes well, with more momentum than the first. There's a slight altercation between a horse and an Orc in the third shot, and one of the floor cameras gets damaged, requiring a quick replacement.

While we're waiting, we visit with LOTR horse coordinator Steve Old and Canadians Lyle Edge and John Scott, who worked on equine-heavy flicks Legends of the Fall, The Unforgiven and Jumanji and are responsible for training LOTR's horses and riders.

Old, a New Zealander, explains that the horses had to be at least 16 hands high and black or brown. (White horses are saved for principals like Theoden and Gandalf.) Each shot uses 25 LOTR stunt horses. Riders--ranging in age from 16 to 75--were auditioned for their horse-handling skills and availability for work. Most riders chose to sleep in tents to be near their horse, with LOTR providing food, showers and nightly movie screenings.

We look twice at a Rohan horseman--he's actually a "she", complete with prosthetic beard. "Move aside, honey," she yells, with a voice like Oprah on acid, "the Rohan girls are comin' to town!"

Second-unit director Geoff Murphy watches from the side, walking back to the monitors to discuss the footage with his assistant directors. Murphy is pleased with the overall effect but wants another take to get more close-ups of the front-line action.

WETA's Taylor suggests the camera be repositioned to show the full mass of the Orc army. The crew agrees to a final take. Murphy is pleased: "The times when we've asked for an extra take, we've gotten some great footage."

Cast and crew record a final frenzied shot, then take a well-deserved break. The Orcs peel off their masks with help from WETA, take a drink and move downfield in preparation the next shot.

The riders stay where they are, for in the next shot they'll literally charge the camera (positioned behind the Orcs). With farther to ride, the Rohirrim work up to a gallop, thundering down the plain. It's both breathtaking and terrifying.

Just when it looks as if we'll be trampled, the horses gallop neatly to our right and out of camera range. (A horse wrangler was cunningly planted among the Orcs to show the horses when to turn.) Adrenaline pumping, cast and crew give a spontaneous round of applause.

WETA special effects will digitally multiply the 175 real-life Rohan riders to create the 6,000-strong army of Tolkien's novel. Stunt riders and soldiers rehearse the close-up work amid prosthetic bodies of dead soldiers and a dead horse made out of what appears to be dark brown Astroturf.

Meanwhile, publicists organize a table where the Orcs write their names and addresses on an envelope and line up obediently to have their individual photos taken as a souvenir. (Photos won't be posted for another two years, after the release of the movies.)

Publicists yell, "Could everyone who wants their head taken off please line up behind me?" while demasked Orcs walk around eating lollipops. It's a surreal, scaly fairy tale.

We chat with the extras as they queue up. Most are locals, but some are ex-army or air force, and a few are tourists, adding a day of Orcing to their overseas adventures.

Work continues throughout the afternoon. Tea and muffins arrive around 4, and the horses, too, are given a well-deserved feed. Clara, a Rohan warrior, says, "This is the kind of work all horse lovers dream of doing!"

It's late afternoon, and the Orcs and Rohan are still toughing it out on camera. But for us, it's back to the plane (with the daily rushes) for a spectacular sunset flight to Christchurch.

As we take off, plumes of white smoke rise from the battlefield. On a clear day, you can see the class struggle forever.